/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.entity.mime;

import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.mime.content.*;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.Args;

import java.io.File;
import java.io.InputStream;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;

/**
 * Builder for multipart {@link HttpEntity}s.
 *
 * @since 4.3
 */
public class MultipartEntityBuilder {

  /**
   * The pool of ASCII chars to be used for generating a multipart boundary.
   */
  private final static char[] MULTIPART_CHARS =
    "-_1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
      .toCharArray();

  private final static String DEFAULT_SUBTYPE = "form-data";

  private ContentType contentType;
  private HttpMultipartMode mode = HttpMultipartMode.STRICT;
  private String boundary = null;
  private Charset charset = null;
  private List<FormBodyPart> bodyParts = null;

  public static MultipartEntityBuilder create() {
    return new MultipartEntityBuilder();
  }

  MultipartEntityBuilder() {
  }

  public MultipartEntityBuilder setMode(final HttpMultipartMode mode) {
    this.mode = mode;
    return this;
  }

  public MultipartEntityBuilder setLaxMode() {
    this.mode = HttpMultipartMode.BROWSER_COMPATIBLE;
    return this;
  }

  public MultipartEntityBuilder setStrictMode() {
    this.mode = HttpMultipartMode.STRICT;
    return this;
  }

  public MultipartEntityBuilder setBoundary(final String boundary) {
    this.boundary = boundary;
    return this;
  }

  /**
   * @since 4.4
   */
  public MultipartEntityBuilder setMimeSubtype(final String subType) {
    Args.notBlank(subType, "MIME subtype");
    this.contentType = ContentType.create("multipart/" + subType);
    return this;
  }

  /**
   * @since 4.4
   * @deprecated (4.5) Use {@link #setContentType(ContentType)}.
   */
  @Deprecated
  public MultipartEntityBuilder seContentType(final ContentType contentType) {
    return setContentType(contentType);
  }

  /**
   * @since 4.5
   */
  public MultipartEntityBuilder setContentType(final ContentType contentType) {
    Args.notNull(contentType, "Content type");
    this.contentType = contentType;
    return this;
  }

  public MultipartEntityBuilder setCharset(final Charset charset) {
    this.charset = charset;
    return this;
  }

  /**
   * @since 4.4
   */
  public MultipartEntityBuilder addPart(final FormBodyPart bodyPart) {
    if (bodyPart == null) {
      return this;
    }
    if (this.bodyParts == null) {
      this.bodyParts = new ArrayList<FormBodyPart>();
    }
    this.bodyParts.add(bodyPart);
    return this;
  }

  public MultipartEntityBuilder addPart(final String name, final ContentBody contentBody) {
    Args.notNull(name, "Name");
    Args.notNull(contentBody, "Content body");
    return addPart(FormBodyPartBuilder.create(name, contentBody).build());
  }

  public MultipartEntityBuilder addTextBody(
    final String name, final String text, final ContentType contentType) {
    return addPart(name, new StringBody(text, contentType));
  }

  public MultipartEntityBuilder addTextBody(
    final String name, final String text) {
    return addTextBody(name, text, ContentType.DEFAULT_TEXT);
  }

  public MultipartEntityBuilder addBinaryBody(
    final String name, final byte[] b, final ContentType contentType, final String filename) {
    return addPart(name, new ByteArrayBody(b, contentType, filename));
  }

  public MultipartEntityBuilder addBinaryBody(
    final String name, final byte[] b) {
    return addBinaryBody(name, b, ContentType.DEFAULT_BINARY, null);
  }

  public MultipartEntityBuilder addBinaryBody(
    final String name, final File file, final ContentType contentType, final String filename) {
    return addPart(name, new FileBody(file, contentType, filename));
  }

  public MultipartEntityBuilder addBinaryBody(
    final String name, final File file) {
    return addBinaryBody(name, file, ContentType.DEFAULT_BINARY, file != null ? file.getName() : null);
  }

  public MultipartEntityBuilder addBinaryBody(
    final String name, final InputStream stream, final ContentType contentType,
    final String filename) {
    return addPart(name, new InputStreamBody(stream, contentType, filename));
  }

  public MultipartEntityBuilder addBinaryBody(final String name, final InputStream stream) {
    return addBinaryBody(name, stream, ContentType.DEFAULT_BINARY, null);
  }

  private String generateBoundary() {
    final StringBuilder buffer = new StringBuilder();
    final Random rand = new Random();
    final int count = rand.nextInt(11) + 30; // a random size from 30 to 40
    for (int i = 0; i < count; i++) {
      buffer.append(MULTIPART_CHARS[rand.nextInt(MULTIPART_CHARS.length)]);
    }
    return buffer.toString();
  }

  MultipartFormEntityNotLimitContentLength buildEntity() {
    String boundaryCopy = boundary;
    if (boundaryCopy == null && contentType != null) {
      boundaryCopy = contentType.getParameter("boundary");
    }
    if (boundaryCopy == null) {
      boundaryCopy = generateBoundary();
    }
    Charset charsetCopy = charset;
    if (charsetCopy == null && contentType != null) {
      charsetCopy = contentType.getCharset();
    }
    final List<NameValuePair> paramsList = new ArrayList<NameValuePair>(2);
    paramsList.add(new BasicNameValuePair("boundary", boundaryCopy));
    if (charsetCopy != null) {
      paramsList.add(new BasicNameValuePair("charset", charsetCopy.name()));
    }
    final NameValuePair[] params = paramsList.toArray(new NameValuePair[paramsList.size()]);
    final ContentType contentTypeCopy = contentType != null ?
      contentType.withParameters(params) :
      ContentType.create("multipart/" + DEFAULT_SUBTYPE, params);
    final List<FormBodyPart> bodyPartsCopy = bodyParts != null ? new ArrayList<FormBodyPart>(bodyParts) :
      Collections.<FormBodyPart>emptyList();
    final HttpMultipartMode modeCopy = mode != null ? mode : HttpMultipartMode.STRICT;
    final AbstractMultipartForm form;
    switch (modeCopy) {
      case BROWSER_COMPATIBLE:
        form = new HttpBrowserCompatibleMultipart(charsetCopy, boundaryCopy, bodyPartsCopy);
        break;
      case RFC6532:
        form = new HttpRFC6532Multipart(charsetCopy, boundaryCopy, bodyPartsCopy);
        break;
      default:
        form = new HttpStrictMultipart(charsetCopy, boundaryCopy, bodyPartsCopy);
    }
    return new MultipartFormEntityNotLimitContentLength(form, contentTypeCopy, form.getTotalLength());
  }

  public HttpEntity build() {
    return buildEntity();
  }

}
